The included prospective randomised controlled trials were appraised according to the following criteria:
whether the patients were randomly assigned to the treatment and whether the randomisation was concealed;
whether all the patients who entered the trial were accounted for at its conclusion;
whether the patients were analysed in the groups to which they were randomised;
whether the patients and clinicians were blinded to which treatment was being received;
aside from the experimental treatment, whether the groups were treated equally; and
whether the groups were similar at the start of the trial.
The authors do not state how the appraisal was conducted.
The authors did not report any assessment of the methodological quality of the observational studies.